The present invention relates to a polymer cemented, thin layer electrode for fuel cells, which electrode is provided with an inactive cover layer on its electrolyte side.
Polymer cemented, porous electrodes made of powdered metals and/or catalytically active electrically conductive powders, such as carbon or tungsten carbide, are known. See, for example, West German Offenlegungsschrift (Laid-Open Application) No. 1,571,750.
Such solid electrodes generally have an electrically conductive surface which will face the electrolyte when they have been built into cells. Care must be taken that anodes and cathodes of this type do not come into contact in cells built of them. Otherwise, an electron loss current will arise. It has been in recognition of this problem that various separator elements have been used in storage batteries.
In fuel cells, in which the electrolyte must circulate in order to regulate the heat, the one type of storage battery separator which has been found practical has been the pierced and corrugated separator. The other types of separators present too much resistance to electrolyte flow.
A disadvantge in the use of these corrugated separators in fuel cells is their significant overall thickness, as compared to cell thickness, and the large volume of electrolyte and weight dictated by their thickness.
For fuel cell electrodes made of loose catalyst powder, it is known to contain the powder by pressing it in layer form with a finely porous cover layer, for example asbestos paper. See West German Offenlegungsschrift (Laid-Open Application) No. 1,930,035. This cover layer absorbs the electrolyte, and a free space for a flow of electrolyte for cooling purposes is completely lacking.